Device in a microtome for holding a grid on which sections are collected

ABSTRACT

According to known art the sections obtained in a microtome are collected floating on a liquid surface. According to the present invention the sections are directly collected onto a grid, for later examination in an electron microscope, by means of a specially designed grid holder.

United States Patent Kindel Dec. 9, 1975 DEVICE IN A MICROTOME FOR HOLDING A GRID 0N WHICH SECTIONS ARE References C t COLLECTED UNITED STATES PATENTS [75] Inventor: Erik Lennart Kindel, Bandhag n 3,225,639 12/1965 Martinelli 83/915.5 X S d 3,377,898 4/1968 Persson 3,460,417 8/1969 Johnson 83/915.5 X [73] Ass1gnee: LKB-Produkter AB, Bromma,

Sweden Primary ExaminerJ. M. Meister [22] Filed: Aug. 23 1974 Assistant ExaminerW. D. Bray [21] Appl. No.: 499,913 [57] ABSTRACT According to known art the sections obtained in a mi- [30] F i A li ati P i i D crotome are collected floating on a liquid surface. Ac- 28 1973 Sweden 7311639 cording to the present invention the sections are directly collected onto a grid, for later examination in 521 US. Cl. 83/167; 83/9l5.5 Gleam micmsmpe by means Specially 51 1m. 01. B26D 7/00 Signed grid [58] Field of Search 83/167, 915.5 4 Claims, 3 Drawing Figures US. Patent Dec. 9 1975 3,924,500

DEVICE IN A MICROTOME FOR HOLDING A GRID ON WHICH SECTIONS ARE COLLECTED The present invention relates to a device in a microtome in which a specimen is sectioned in thin sections by a knife, the knife being arranged in a knife attachment, for collecting of sections obtained.

In sectioning in a microtome of a specimen, e.g. a biological specimen, there is generally utilized a knife consisting of a glass prism. The knife is usually arranged in a knife attachment, comprising two rectangular members situated on each side of the glass prism. Usually the several sectionings are performed consecutively, while the sections in a suitable manner have to be caught up in the vicinity of the knife edge when waiting for further processing, as investigation in an electron microscope. In sectioning in a microtome at room temperature this is usually achieved in such a way that the parallel members of the knife attachment, in combination with a suitably attached tape strip, form a trough which is filled with a liquid onto which the achieved successive sections are made to float. By suitable means, like an eyelash, the sections may after completed sectioning be transferred to a so-called grid, that is a circular copper net, for investigation in an electron microscope. In certain sectioning work at low temperature, as in cytochemical work, it is quite unsuitable to risk chemical interference from such a liquid.

In many kinds of sectioning in a microtome it is however desired to work at a low temperature, eg from l70 to l80C. Then it is impractical to work with a trough filled with a liquid, onto which the sections are made to float. Then the sections may be deposited onto the declining face of the prism shaped glass knife. Thereafter, they ought to be caught up by a suitable means, e.g. an eyelash, and be placed onto a grid. However, in work at this low temperature, the knife as well as the specimen are contained in a thermally isolated container, the inside of which is kept cold by e.g. liquid nitrogen. When handling of the sections then this container has to be opened whereby the temperature will rapidly arise. Accordingly, it would be valuable to provide a device for collecting the sections, which permits as rapid handling of the sections achieved as possible.

The present invention relates to a device by means of which the sections are caught up directly on the grid which is designed for later investigation of the sections in an electron microscope. By means of the device according to the present invention the grid may be moved to that location along the knife edge where the most effective sectioning is obtained or to that position along the knife edge where the most interesting part of the specimen will hit the knife edge. By the device according to the present invention the sections caught up on the grid may rapidly be removed for the smallest possible temperature rise during this operation step.

The characteristics of the invention are obvious from the claims following the specification.

The invention will now be further explained with reference to the attached drawing showing by way of example a preferred embodiment.

FIG. 1 shows a perspective sketch of a knife and a knife attachment in a microtome;

FIG. 2 shows a perspective sketch of a device according to the invention, viewed from below; and

FIG. 3 shows a perspective sketch of the same device seen from above.

In FIG. I, the number 1 denotes a knife consisting of a triangular glass prism having the knife edge 2, 3 and 4 denote two rectangular members forming parts of the knife attachment. In the opening 5 formed by the rectangular members, a wall can 'be inserted so that the knife attachment will form a trough which may be filled with a liquid.

In FIG. 2 the grid holder according to a preferred embodiment of the invention comprises a middle plate 6 having an upper plate 7 slidably applied on top of it and a block 8 attached under it. Between the plates 6 and 7 there is formed an aperture 9 in which a grid 10 can be inserted.

In FIG. 3 the number 11 denotes two bored holes by means of which the grid holder and grid can easily be handled by means of a pair of forceps. The sliding displacement of the upper plate 7 is governed by the pins 12 in the openings 13. v

The device according to the invention works in the following way:

Instead of having the knife attachment forming a trough as in the known art the grid holder is instead positioned onto the upper ridges of the rectangular members 3 and 4, whereby the plate 6 of the grid holder will rest upon these. The purpose of the block 8 is to exert guiding action against the rectangular members 3 and 4, the grid holder then being displaceable in direction towards the knife edge 2, essentially perpendicularly against this or in an angle determined by the design of the knife attachment. The grid 10 can easily be inserted into the aperture 9. The block 8 can, of course, be substituted by two governing blocks. It is preferred that the rectangular members 3 and 4 have the same height whereby the aperture 9 will be horizontal. The grid holder with the grid 10 is displaced towards the knife in order that the grid 10 is brought in contact with the knife in close vicinity to the knife edge 2. The aperture 9 then should have such a length that the grid 10 can be displaced laterally to that point where the knife edge is sharpest or to that point where the most interesting part of the specimen is hitting the knife edge.

After a suitable number of sections have been collected on the grid, the grid holder can simply be lifted by means of a pair of forceps by the bored holes 11. Alternatively gripping means for rapid handling by means of a pair of forceps should not fall outside the scope of the invention. When the grid holder is in collecting position in the vicinity of the knife edge the upper plate 7 is in its rear position as shown in the figures. When the grid holder and grid are lifted away and the grid should be removed from the grid holder the upper plate 7 is simply displaced in the direction of the grid so as to push it off from the grid holder.

The aperture 9 may alternatively be made in a simpler way. For instance the upper plate 7 may be dispensed with and the aperture 9 be designed as a slit in the plate 6. A portion of the plate 6 then could be bent for horizontal insertion of the grid 10. The upper ridges of the rectangular members 3 and 4 usually are horizontal but could also incline by a small angle. Also, the aperture 9 can be designed in order that the grid 10 is inserted in the aperture in a plane parallel to the plane of the plate 6. The invention also embraces devices where the grid is forming an angle against the plate 6.

When sectioning with a knife without knife attachment the grid holder could instead by provided with suitable attachment, providing for the grid keeper to 3 move directly towards the knife.

By the device according to the invention thus a number of sections can be collected onto the grid 10, while the specimen and knife are situated in an isolated space under a low temperature whereafter the grid by the grid holder rapidly and simply can be displaced within said space without too great a temperature influence.

I claim:

1. Device for use in microtomes of the type wherein thin sections of material cut by a knife means are to be collected on a grid, comprising a grid holder, means for mounting the grid holder on said knife means for movement toward and away from the knife edge of said knife means in the plane within which said knife edge is contained, said grid holder being provided with a recess facing said knife edge for removably supporting a grid close to the knife edge to collect specimens cut by the knife means.

2. The invention defined in claim 1, wherein said means for mounting the grid holder includes a knife holder having spaced walls provided with generally horizontal upper margins, said grid holder being slidable on said upper margins.

3. The invention defined in claim 2, wherein said grid holder comprises a flat element having guide means on the lower surface thereof for sliding engagement with the inner surfaces of the spaced walls, said recess extending across the width of one margin of said element.

4. The invention defined in claim 1, wherein said grid holder comprises a pair of rectangular flat members connected together for relative slidable adjustment, said recess being formed in the end margin of at least one of said members. 

1. Device for use in microtomes of the type wherein thin sections of material cut by a knife means are to be collected on a grid, comprising a grid holder, means for mounting the grid holder on said knife means for movement toward and away from the knife edge of said knife means in the plane within which said knife edge is contained, said grid holder being provided with a recess facing said knife edge for removably supporting a grid close to the knife edge to collect specimens cut by the knife means.
 2. The invention defined in claim 1, wherein said means for mounting the grid holder includes a knife holder having spaced walls provided with generally horizontal upper margins, said grid holder being slidable on said upper margins.
 3. The invention defined in claim 2, wherein said grid holder comprises a flat element having guide means on the lower surface thereof for sliding engagement with the inner surfaces of the spaced walls, said recess extending across the width of one margin of said element.
 4. The invention defined in claim 1, wherein said grid holder comprises a pair of rectangular flat members connected together for relative slidable adjustment, said recess being formed in the end margin of at least one of said members. 